U.S. patent number 4,570,853 [Application Number 06/536,980] was granted by the patent office on 1986-02-18 for self-cleaning fuel injection valve.
This patent grant is currently assigned to Daimler-Benz Aktiengesellschaft. Invention is credited to Kurt Schmied.
United States Patent |
4,570,853 |
Schmied |
February 18, 1986 |
**Please see images for:
( Certificate of Correction ) ** |
Self-cleaning fuel injection valve
Abstract
A fuel injection nozzle is proposed with an opening needle
opposed against the flow direction and in which a spring loaded
abutment body is guided for longitudinal sliding movement, which
body with its free end protrudes into a blind pocket reservoir of
the nozzle after a successful injection. Before the beginning of
the injection this blind pocket reservoir is opened to open
injection holes with different injection directions branching off
from the blind pocket reservoir. Through a nozzle embodiment of
this kind the damaging space in the blind pocket reservoir is
substantially avoided and the proportion of the unburned
hydrocarbons is substantially reduced.
Inventors: |
Schmied; Kurt (Denkendorf,
DE) |
Assignee: |
Daimler-Benz Aktiengesellschaft
(Stuttgart, DE)
|
Family
ID: |
6174453 |
Appl.
No.: |
06/536,980 |
Filed: |
September 29, 1983 |
Foreign Application Priority Data
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Sep 29, 1982 [DE] |
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3236046 |
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Current U.S.
Class: |
239/116;
239/533.3 |
Current CPC
Class: |
F02M
45/086 (20130101); F02M 61/18 (20130101); F02M
2200/46 (20130101) |
Current International
Class: |
F02M
61/18 (20060101); F02M 61/00 (20060101); F02M
45/08 (20060101); F02M 45/00 (20060101); F23D
014/50 (); B05B 015/02 () |
Field of
Search: |
;239/533,533.1-533.12,584,583,123,87,115-118 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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28288 |
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May 1981 |
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EP |
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2147719 |
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Sep 1971 |
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DE |
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102198 |
|
Dec 1973 |
|
DE |
|
2711392 |
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Sep 1978 |
|
DE |
|
3002129 |
|
Sep 1980 |
|
DE |
|
69754 |
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May 1980 |
|
JP |
|
57462 |
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Nov 1969 |
|
PL |
|
2003550 |
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Mar 1979 |
|
GB |
|
2084248 |
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Apr 1982 |
|
GB |
|
Primary Examiner: Kashnikow; Andres
Assistant Examiner: Weldon; Kevin
Attorney, Agent or Firm: Barnes & Thornburg
Claims
I claim:
1. Fuel injection nozzle arrangement for an internal combustion
engine, comprising:
a nozzle body;
an injection needle movably disposed in the nozzle body and
engageable with a needle seat at the nozzle body,
a pocket reservoir formed at the downstream end of the needle seat,
injection holes with different injection directions extending from
the pocket reservoir such that a bottom surface of the pocket
reservoir lies below a level at which the injection holes open into
said reservoir, allowing fuel to be trapped in said reservoir
following an injection cycle;
an abutment body movably disposed in the needle between a first
position blocking the pocket reservoir and a second position
freeing the pocket reservoir, said abutment body extending into an
area of the reservoir adjacent to the injection holes to at least
partially block said injection holes and to substantially fill said
reservoir when said abutment body is in said first position;
abutment body biasing means for biasing said abutment body toward
said first position blocking the pocket reservoir, and;
wherein said abutment body, injection needle and biasing means are
configured so that said abutment body is removed to the second
position prior to movement of the injection needle to begin the
injection cycle, and wherein said abutment body is moved to the
first position immediately following the injection cycle to force
the trapped fuel from the reservoir.
2. Arrangement according to claim 1, wherein said biasing means is
a return spring interposed between the abutment body and the
injection needle.
3. Arrangement according to claim 2, wherein the return spring,
which is disposed at the back side of the abutment body, is
provided in the lower half of the needle shaft of the injection
needle, and wherein the abutment body is moved against the return
spring by means of the combustion space pressure of the engine
during the compression phase.
4. Arrangement according to claim 2, with through bores extending
in the nozzle body and leading to a pressure chamber surrounding
the injection needle, wherein the abutment body itself extends over
the entire length of the injection needle and exhibits a pressure
shoulder for effecting lifting of the abutment body via the fuel
pressure, which pressure shoulder is disposed in the region of one
of the pressure spaces formed out of the injection needle and the
abutment body, and wherein at least one connecting bore is
connected with the chamber surrounding the injection needle
adjacent the pressure shoulder.
5. Arrangement according to claim 2, wherein the abutment body is
disposed to mate with the form of the reservoir at its free
end.
6. Arrangement according to claim 3, wherein the abutment body is
disposed to mate with the form of the reservoir at its free
end.
7. Arrangement according to claim 4, wherein the abutment body is
disposed to mate with the form of the reservoir at its free
end.
8. Arrangement according to claim 5, wherein the branching
injection holes from the reservoir are closeable by means of the
abutment body.
Description
BACKGROUND AND SUMMARY OF THE INVENTION
The invention relates to a fuel injection nozzle for combustion
engines of the type having a nozzle body, an injection needle
slidably disposed in the nozzle body, and a reservoir space
downstream of the injection needle seat.
It is known that the various legislators have established ever
higher demands regarding the exhaust emissions from internal
combustion engines. This is especially so for unburned hydrocarbons
wherein a very low value has been prescribed, which through the
prior art injection nozzles can scarcely be achieved. It is further
known that after the closing of an injection nozzle after a
successful injection, there is remaining fuel in the blind pocket
reservoir, which does not take part fully in the combustion and is
responsible in large measure for the undesirable hydrocarbon
emmissions.
With injection nozzles with a minimum pocket reservoir (DE-OS No.
24 38 014), an abutment body formation effective at the injection
nozzle tip is fully dived or extended into the pocket reservoir and
there are resultant disadvantages in fuel efficiency and smoke. The
remaining cross section between the pocket reservoir walls and the
abutment body throttles the flow of fuel too strongly.
With injection nozzles of the so-called seating hole type nozzles
(DE-OS No. 27 10 217)--provided with injection holes in the
injection needle seat to open, they reduce the hydrocarbon
emmission about approximately the half value, however, this form of
embodiment is not disposed for an error free construction for
series production. Injection nozzles of this kind fail by means of
the nozzle tip rubbing off. A further disadvantage results because
the strong turning of the combustion field out the slot at the
cross section of the needle seat in the tip holes does not provide
the full fuel pressure at the injection openings. The injection
intensity is thereby reduced.
Good efficiency and smoke value is achieved only with optimal flow
comparisons in the fuel nozzle. Thereby, it is furthermore
necessary to have a nozzle with bottom pocket reservoirs.
The invention is based upon the problem to minimize the effects of
the space in the pocket reservoir adjacent the fuel injection
nozzle tip and simultaneously to increase the through flow
characteristics at the needle seat.
According to the invention, a movable abutment body is slidably
disposed in the injection needle to selectively block and free-up
the reservoir space and the opening therefrom. The abutment body
and needle are separated by a return spring biasing the abutment
body to a position filling the reservoir space. The return spring
and the pressure surfaces on the injection needle and abutment body
are configured so that the reservoir space is free during initial
injection and then the abutment body squeezes out any fuel in the
reservoir space, thereby reducing engine hydrocarbon emissions.
Through the movement of the abutment body relative to the injection
needle, the pocket reservoir is timely fully filled. To begin the
injection, this abutment body is, either by means of the combustion
room pressure of the engine, or through the fuel pressure in the
pressure space, protruded into the injection nozzle. The pocket
reservoir is then free and the fuel can stream unhindered into the
tip holes, i.e., injection holes.
At the end of the injection procedure the injection nozzle closes
in a normal manner and through the strength of the return spring,
the outwardly moving abutment body (with respect to the injection
needle) forces the remaining fuel within the pocket reservoir into
the combustion room.
An illustrative example of the invention is shown in the drawing
and is described in more detail below.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a longitudinal schematic sectional view through a fuel
injection nozzle with a corresponding abutment body in the
injection needle, movable by the combustion space pressure of the
engine, constructed in accordance with a first preferred embodiment
of the invention; and
FIG. 2 is a longitudinal schematic sectional view through a fuel
injection nozzle, which has a correspondingly guided abutment body
in the injection needle which is biased by the fuel pressure in the
nozzle, constructed in accordance with a second preferred
embodiment of the invention.
DETAILED DESCRIPTION OF THE DRAWINGS
In FIG. 1 there is shown the lower part of a fuel injection nozzle
1 for a combustion engine, which includes a nozzle body 2 in which
there is an injection needle 3, disposed against the flow direction
of the fuel. A through bore 4 is provided which fuel from an
unillustrated injection pump into the injection needle 3 and the
surrounding pressure chamber 5. The injection nozzle exhibits a
ball formed needle seat 6 as well as a pocket reservoir 7
(downstream) upstream of this needle seat 6. Injection openings 8
with different injection directions branch off at the reservoir 7,
in this pocket reservoir 7 into which spring loaded abutment body 9
protrudes, which body 9 has a ball formed free end in the shape of
the pocket reservoir 7, of the kind that it closes the through
openings 10 of the holes 8.
The abutment body 9 is formed as a small piston guided for
longitudinal slided movement in injection needle 3 against the
force of a return spring 11 and extends itself as well as the
return spring 11 being of approximately the same length, only over
a small part of the smaller diameter and portion of the needle
shaft 3a. The other connection from the small to the larger needle
shaft 3b is by means of a pressure shoulder 12 formed in the
pressure chamber 5, through which the injection needle 3 due to the
incoming pressure waves lifts up from its ball formed needle seat
6. Prior to the lifting up of injection needle 3, the abutment body
9 is already pushed against the strength of the return spring 11
into the injection needle 3 by the effective combustion chamber
pressure in the compression phase of the engine, so that the fuel
can flow unhindered into the then free reservoir 7 and the
injection holes 8.
As soon as the injection needle 3 is further lifted off of the
needle seat 6, the abutment body 9 is again protruding outwardly of
the needle shaft 3a into the reservoir hole 7 and presses aside the
hazardous remaining fuel.
With the embodiment according to FIG. 2 the abutment body 9' is
guided, not through the combustion chamber pressure of the
combustion engine as in the FIG. 1 embodiment, but rather, as well
as the injection needle 3'--through the injection pressure of the
injection system. In FIG. 2, corresponding parts as in the FIG. 1
embodiment are designated with primed reference characters. The
abutment body 9' is therefore formed as an abutment needle with
pressure shoulder 13, which borders pressure space 14, which is
disposed between the nozzle needle 3' and the abutment needle 9'
and is connected by means of connecting bores 15 with the
surrounding pressure chamber 5' at the nozzle needle 3'. The
abutment needle 9' extends itself over the entire length of the
injection needle 3' and protrudes with its needle point 16 into the
reservoir pocket 7'. The return spring 11' for the abutment needle
9' is arranged concentrically to the closing spring 17 for the
nozzle 3'. The abutment needle 9' is so pretensioned that it is
lifted by the injection system oncoming pressure waves to at first
open the reservoir 7'. Subsequently the injection pressure opens
the nozzle needle 3. The return spring 11' acts to subsequently
force the needle 9' to squeeze out the fluid in reservoir 7, at the
end of the injection.
Although the present invention has been illustrated in detail, it
is to be clearly understood that the same is by way of example only
and is not be taken by way of limitation. The spirit and scope of
the invention are to be limited only by the claims.
* * * * *